Portable performance stages that can be transported over highways from one performance to another are known. U.S. Pat. No. 3,620,564 owned by the assignee of this application discloses a self-propelled portable stage. U.S. Pat. No. Re. 34,468 issued to Rau et al., also owned by the assignee of this application, discloses a portable performance platform, including a chassis mounted on ground engaging wheels configured for towing behind an automobile or truck. The portable performance platform has a folded stowed configuration for transportation along roads and highways and an unfolded configuration presenting an extended performing stage area having an overhead canopy. The overhead canopy is formed from a side wall and a top wall elevated from the stowed configuration by a set of at least four hydraulic piston and cylinder assemblies. A stage extending apron is lowered by a third set of two piston and cylinder assemblies. Rau teaches raising the canopy through the use of the plurality of independent hydraulic pistons and cylinders and mechanically locking the articulating arms in place with locking pins inserted through aligned holes.
Anytime pistons and cylinders are used, there is a danger of hydraulic failure. Such an occurrence with the pistons supporting the upper roof panel of the Rau device in its lifted position would permit the upper roof panel to swing back down endangering anyone standing on or in front of the stage. The canopy, formed of the upper and lower roof panels, is made safe and secure with mechanical locking pins. A design that would guard against hydraulic failure without the requirement for mechanical locking pins would greatly assist setup and takedown of the canopy.
Additionally, a portable performance platform such as the Rau device should be secure from the weather in both the stowed configuration and the extended performing configuration. A design that would prevent the entry of rain into the stage area, either by flowing into or being blown into the joint between upper and lower roof panels, would enhance the use of the platform.
A portable performance platform that is capable of supporting an over head canopy from the far side, or back, wall which is capable of controlling rain falling onto the canopy would be desirable. Additionally, a portable performance platform with a canopy safely positionable in a variety of angles and elevations and hydraulically locked in the performance configuration without the use of mechanical pins would also be desirable.